Chapter 11: Functional Organization of Nervous Tissue

Flashcards for Chapter 11 Lecture Notes on Functional Organization of Nervous Tissue

Nervous System

The communication system consisting of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves, ganglia, and receptors).

Central Nervous System (CNS)

The master control system responsible for the function of everything in the body, including interpreting sensory input and dictating motor output.

Nerve

Bundle of axons located outside the brain and spinal cord.

Cranial Nerves

Nerves that originate from the brain; there are 12 pairs.

Spinal Nerves

Nerves that originate from the spinal cord; there are 31 pairs.

Ganglion

Collection of neuron cell bodies located outside the brain and spinal cord.

Plexus

Extensive network of axons, and sometimes neuron cell bodies, located outside the CNS.

Glial Cells

Supportive cells in the nervous system with many functions.

Maintaining Homeostasis

To regulate and coordinate activities to maintain balance within the body.

Receiving Sensory Input

To monitor internal and external stimuli.

Integrating Information

The process by which the brain and spinal cord interpret sensory input.

Generating Responses

To control muscles and glands.

Establishing and Maintaining Mental Activity

Consciousness, thinking, memory, and emotion.

Central Nervous System (CNS)

Brain and spinal cord of dorsal body cavity; integration and control center; interprets sensory input and dictates motor output.

Peripheral Nervous System (PNS)

The portion of nervous system outside CNS; consists mainly of nerves that extend from brain and spinal cord.

Sensory (Afferent) Division

Transmits action potentials from receptors toward the CNS.

Sensory Receptors

Neuron endings or specialized cells that detect external and internal stimuli; send input along nerves to brain or spinal cord.

Motor (Efferent) Division

Transmits action potentials from CNS to effectors (muscles, glands).

Somatic Nervous System

From CNS to skeletal muscles; voluntary; single neuron system.

Autonomic Nervous System (ANS)

From CNS to smooth muscle, cardiac muscle, and certain glands; subconscious or involuntary control; two neuron system.

Sympathetic Division

Prepares body for physical activity; 'fight or flight'.

Parasympathetic Division

Regulates resting functions such as digesting food or emptying of the urinary bladder; 'rest and digest'.

Enteric Division

Plexuses within the wall of the digestive tract.

Neurons

Electrically excitable cells of the nervous system.

Cell Body

Large nucleus and nucleolus; perikaryon (cytoplasm); Rough ER / Nissl bodies (synthesizes proteins); Mitochondria (produces energy).

Dendrites

Branched processes of cell body that receive information.

Dendritic spines

Short branched extensions of dendrites, receives information from other neurons, conduct currents toward the cell body

Axolemma

Plasma membrane that covers axoplasm

Terminal

Region that secretes neurotransmitters, which are released into extracellular space

Axons

Conducting region of neuron, generates nerve impulses and transmits along neuron cell membrane to axon terminal - action potential.

Collaterals

Branches of axon.

Axon hillock

Region of initial attachment of axon to cell body

Sensory or Afferent Neurons

Action potentials toward CNS.

Motor or Efferent Neurons

Action potentials away from CNS.

Interneurons

Within CNS from one neuron to another.

Multipolar Neurons

Most neurons in CNS; motor neurons.

Bipolar Neurons

Sensory in retina of the eye and nasal cavity.

Pseudo-Unipolar Neurons

Single process that divides into two branches. Part that extends to the periphery has dendrite-like sensory receptors.

Anaxonic Neurons

No axons, only dendrites; found in brain and retina where they only communicate using graded potentials.

Astrocytes

Star-shaped glial cells with processes that form feet that cover the surfaces of neurons, blood vessels, and the pia mater.

Choroid Plexus

Specialized ependymal cell within certain regions of ventricles that secrete cerebrospinal fluid.

Ependymal Cells

Line brain ventricles and spinal cord central canal.

Microglia

Specialized CNS macrophages that respond to inflammation and phagocytize necrotic tissue and microorganisms.

Oligodendrocytes

Glial cells with small bodies and few processes that form insulating myelin sheaths to increase the speed of action potentials.

Schwann Cells

Wrap around portion of only one axon to form myelin sheath. Outer layer of the wrap is the neurilemma that contains most of the cytoplasm, nucleus and organelles.

Satellite Cells

Surround neuron cell bodies in sensory and autonomic ganglia; provide support, nutrients, and protection from heavy-metal poisons.

Nodes of Ranvier

Gaps in the myelin sheath where the axon is exposed.

Gray Matter

Unmyelinated axons, cell bodies, dendrites involved in integrative functions. The cortex of the brain is gray matter.

White Matter

Myelinated axons that propagate action potentials.

Nuclei

Clusters of neuron cell bodies in the CNS.

Nerve Tracts

Bundles of myelinated axons in the CNS.

Ganglia

Clusters of cell bodies in the PNS.

Nerves

Bundles of axons with their connective tissue sheaths in the PNS.

Action Potentials

Electrical signals produced by cells that allow perception of the environment, performance of complex mental activities, and responses to stimuli.

Membrane Potential

The result from ionic concentration differences across plasma membrane and permeability of membrane.

Electrochemical Gradient

Electrical and chemical gradients combined.

Ligand-gated Channels

open or close in response to ligand such as neurotransmitter or hormone binding to receptor protein. Receptor proteins are usually glycoproteins

Voltage-gated Channels

open or close in response to specific, small voltage changes across the cell membrane

Leak Ion Channels

Also called nongated ion channels; Always open and responsible for permeability when membrane is at rest

Depolarization

Movement of resting membrane potential toward zero

Hyperpolarization

Movement of resting membrane potential farther away from zero